emit unpublish event also for local participant

[lukasIO]

but only if it was caused by mediatrack ended event.

Reasoning:
When screensharing is stopped via browser UI, it comes in handy to subscribe to TrackUnpublished

this.currentRoom.localParticipant.on(ParticipantEvent.TrackUnpublished, async (track) => {
			log.debug('local track unpublished (most likely by browser), stop screen share');

the naming and default behaviour is mirrored from RemoteParticipant.ts

[davidzhao]

This is a good call @lukasIO. We've been talking about how to handle this across all of our SDKs in a consistent manner. The challenge with using TrackUnpublished is that it's supposed to only reflect a remote track (as defined by the docs today).

We'll discuss and update this PR with feedback.

[lukasIO]

closing in favor of #72